1. Field of the Invention
This invention relates to fluid-operated actuating devices of the type including an actuating cylinder member, an axially movable actuating piston rod member, and actuating fluid connection means for introducing actuating fluid to and removing actuating fluid from the actuating cylinder member so as to adjust the relative axial position of the actuating cylinder and piston members, and pertains in particular to new and improved structure for damping the movement of the piston rod member with respect to the cylinder member.
2. The Prior Art
It is known from U.S. Pat. No. 2,624,318 to provide a damping cylinder member and a damping piston rod member, one of said damping members being fastened to one of said actuating members and the other of said damping members being fastened to the other of said actuating members. The damping piston rod member in this known construction is fastened to a damping piston unit axially movable within said damping cylinder member, and flow passage means are provided for connecting two damping chambers defined within said damping cylinder by said damping piston unit. Damping valve means are associated to said flow passage means for varying the flow cross-section of said flow passage means. For operating said damping valve meansfrom a location outside said damping cylinder member said damping piston rod member is provided with an axially extending bore. Rod means extend through said bore from a handle provided outside said damping cylinder member to said damping valve means. The rod means are rotatable by said handle and transmit rotation to said damping valve means, said damping valve means being designed as rotary valve means.
This known device does not allow a precise and highly sensitive adjustment of the flow cross-section of said flow passage means so that it is not possible to adjust the flow cross-section of said flow passage means as precisely as desired.